The present invention relates to a heater power and control circuit for use in a heating, ventilation and air-conditioning ("HVAC") system. In particular, the present invention relates to an improved system and method for controlling the temperature of a resistance heater in an HVAC system.
Although thermal overload protection has been used for many years with HVAC resistance heaters to sense and control when the heater temperature exceeds a predetermined level, there is still room for improvement in the design and operation of such circuits. In particular, as will be explained further below, prior art designs for sensing and controlling the temperature of resistance heaters in HVAC systems may not address certain issues encountered in situations of thermal overload. Accordingly, it would be desirable to be able to provide an improved heater power and control circuit for use in an HVAC system. It would also be desirable to be able to provide an improved method for controlling the temperature of a resistance heater in an HVAC system.